Over-the-counter medications can cause serious side effects in your pet. Contact your veterinarian before using any over- the-counter medication and follow your veterinarian’s directions.
What is acetylsalicylic acid (aspirin)?
Acetylsalicylic acid, or ASA (brand name: Aspirin®), is an anti-inflammatory, anti-clotting, fever-reducing, and pain-controlling medication, used most for its anti-clotting effects in many pets.
Its use in cats, dogs, and small mammals to treat excessive clotting, inflammation, fever, and pain is off label (extra label). Many drugs are commonly prescribed for off-label use in veterinary medicine. “Off label” means the drug is being used in a way that has not been reviewed or approved by the U.S. Food and Drug Administration (FDA) or Health Canada. In these instances, follow your veterinarian’s directions and cautions carefully, as they may be significantly different from those on the label.
How is aspirin given?
- Aspirin is given by mouth in the form of a tablet, preferably an enteric-coated tablet.
- Give with food.
- If your pet acts sick or vomits, contact your veterinarian.
This medication should take effect within 1 to 2 hours; however, effects may not be noted outwardly, and laboratory tests may need to be done to evaluate this medication’s effectiveness.
What if I miss giving my pet the medication?
If you miss a dose, give it as soon as you remember, and then wait the recommended amount of time between doses. Do not give the pet two doses at once.
Are there any potential side effects?
Aspirin can affect the gastrointestinal tract, with the following side effects:
- nausea
- decreased appetite
- vomiting
- intestinal irritation
Serious adverse reactions associated with this drug may occur without warning and could, in rare cases, lead to death. If any of the following signs develop, stop giving aspirin and contact your veterinarian immediately:
- Indications of bleeding of the gastrointestinal (GI) tract. Signs of bleeding in the GI tract include:
- black/tarry stools
- blood or “coffee grounds” in the vomit
- frank blood in the stools
- anemia or low blood protein can occur in cases of severe bleeding
- In cats, aspirin may cause acidosis.
This moderate-acting medication should stop working in a few days, although effects can be longer in pets with liver or kidney disease.
It is important to dose your cat carefully, as cats are very sensitive to aspirin. If dosed incorrectly, aspirin can build up in your cat’s system and cause toxic effects, because aspirin clears more slowly from a cat’s system. Kidney and liver damage can occur. Follow your veterinarian’s instructions carefully.
Are there any risk factors for this medication?
Aspirin SHOULD NOT BE USED in pets that:
- are allergic to it,
- have bleeding ulcers
- have bleeding disorders
- have asthma
- have kidney failure
- are pregnant (unless as a last resort)
Aspirin should be USED WITH CAUTION in pets that:
- have severe liver failure
- have decreased kidney function
- have low blood protein.
- are newborn
If possible, aspirin should not be used one week prior to surgical procedures.
Aspirin must be USED CAUTIOUSLY AND DOSED VERY CAREFULLY in cats.
Are there any drug interactions I should be aware of?
Avoid giving your pet other NSAIDs or corticosteroids while they are taking aspirin, unless directed by your veterinarian. Certain medications may interact with aspirin, so it is important to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking before starting any new treatment.
MEDICATIONS OF CONCERN include:
- ACE inhibitors like benazepril (Fortekor®) or enalapril (Enacard®)
- furosemide
- glucosamine
- heparin
- pentosan polysulfate sodium (Cartrophen®)
- phenobarbital
- vitamin E
Is any monitoring needed with this medication?
- Your veterinarian may perform baseline bloodwork, urinalysis, and blood pressure assessment before your pet starts aspirin.
- Your veterinarian may monitor your pet to be sure that the medication is working.
- If needed, your veterinarian may monitor for bleeding or anemia.
- At home, monitor for any side effects such as those noted above. If any side effects occur, discontinue the medication and contact your veterinarian.
How do I store aspirin?
- Store aspirin in a tight container, away from light and moisture.
- If the medication has a vinegar-like odor, do not use it.
- Keep the container out of reach of children and pets.
- Store compounded forms of this medication according to the label.
What should I do in case of emergency?
If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions for contacting an emergency facility.
